Not applicable.
Not applicable.
The invention relates generally to medical devices and procedures. More particularly, this invention relates to an absorbable bone anchor system for attaching soft tissue to hard bone, and to methods for attaching soft tissue to hard bone.
Soft tissues, such as ligaments, tendons and muscles, are attached to a large portion of the human skeleton. In particular, many ligaments and tendons are attached to the bones which form joints, such as shoulder and knee joints. A variety of injuries and conditions require attachment or reattachment of a soft tissue to bone. For example, when otherwise healthy tissue has been torn away from a bone, surgery is often required to reattach the tissue to the bone to allow healing and a natural reattachment to occur.
A number of devices and methods have been developed to attach soft tissue to bone. These include screws, staples, cement, suture anchors, and sutures alone. Some of the more successful methods involve use of a suture anchor to attach a suture to the bone, and tying the suture in a manner that holds the tissue in close proximity to the bone.
The tissue may be attached to the bone during open surgery, or during closed (e.g., arthroscopic) surgical procedures. Closed surgical procedures are preferred since they are less invasive and are less likely to cause patient trauma. In a closed surgical procedure, the surgeon performs diagnostic and therapeutic procedures at the surgical site through small incisions, called portals, using instruments specially designed for this purpose. One problem encountered in the less invasive, closed surgical procedures is that the surgeon has significantly less room to perform the required manipulations at the surgical site. Thus, devices and methods are needed which will allow a surgeon to effectively and easily attach tissue to bone in the small spaces provided by less invasive surgical procedures.
Proper attachment of soft tissue requires that it be placed in the anatomically correct position to promote optimal healing. Conventional methods for attaching soft tissue to bone have typically used toggling anchors having sutures attached thereto. The sutures enable the soft tissue to be adjustably tied down in proximity to the bone surface after the anchor is inserted in a predrilled bone cavity. However, the suture strands extending from the bone anchor can often encumber the area in which the bone anchor is introduced, leading to less than ideal engagement of the anchor in the cavity. In a situation where the bone cavity needs to be larger than the bone anchor to provide clearance for both the suture strands and the anchor, it is difficult to then effect sufficient engagement of the anchor to the bone.
There is thus a need for an improved system for anchoring soft tissue to bone which provides optimal purchase into bone to prevent loosening of the anchor in the bone cavity. Further, there is a need for an improved system for anchoring soft tissue to hard bone which enables suture strands to be located on the same side of the anchor body in order to maximize the area of the leading surface of the bone anchor which engages bone, resulting in increased engagement and resistance to tensile forces. It would also be advantageous to provide a fully absorbable suture anchor and system.
The present invention avoids the aforementioned problems associated with conventional toggling anchors by providing a bone anchor that can toggle in two planes for secure anchorage within a bone cavity. The bone anchor is configured such that the suture strands can be located on the same side of the anchor body to maximize the area of the leading surface which engages bone, resulting in increased engagement and resistance to tensile forces.
In an exemplary embodiment of the present invention, a bone anchor is provided for anchoring tissue to bone having an elongate body extending between a first leading end and a second trailing end. The elongate body defines a longitudinal axis of the anchor. Between the first and second ends are two opposed surfaces and a plurality of sidewalls adjacent to and extending between the two opposed surfaces. Extending from one of the sidewalls is a flared portion configured to engage and anchor into bone. The elongate body also includes at least one suture channel for passage of a suture strand therethrough. The suture channel is obliquely angled with respect to the longitudinal axis such that applying tension to a suture strand extending through the suture channel will force the bone anchor to toggle in two planes. This two-way toggling action enables a better interference fit of the bone anchor in the bone cavity.
In one aspect of the present invention, the bone anchor may include a notch for engaging a portion of the suture strand. The anchor may also include two suture channels. Preferably, the suture channels are misaligned with respect to the longitudinal axis of the body. A fin extending from one of the sidewalls can also be included.
In another aspect of the present invention, the bone anchor can include an elevated region that includes extra material near the first leading end of the body. Bone anchor can also include a depressed region near the second trailing end wherein material is removed from this depressed region to provide clearance for the suture thread.
In a preferred embodiment, the bone anchor can be entirely bioabsorbable. However, the bone anchor may also be formed of a non-absorbable polymer or metal. A method is also provided by which a detached tissue may be securely attached to bone in an anatomically correct position using the bone anchor of the present invention.
Further features of the invention, its nature and various advantages, will be more apparent from the accompanying drawings and the following detailed description of the drawings and the preferred embodiments.